EP2091029B2 - Hazard recognition utilising a temperature measurement device integrated in a microcontroller - Google Patents

Abstract

The detector (100) has an optical measuring device for detecting a physical measuring variable and transmitting measurement signals indicative of a preset dangerous situation e.g. smoke. A microcontroller (120) is downstream of the device and evaluates the signals. A temperature measuring diode (125) detects absolute temperature and transmits a temperature measurement signal indicative of the detected temperature. The diode is integrated in the microcontroller that considers the temperature measuring signal during the evaluation of the measurement signals. Independent claims are also included for the following: (1) a method for detecting a dangerous situation (2) a computer-readable storage medium comprising a program that is executed by a microcontroller of a danger detector to perform a method for detecting a dangerous situation (3) a program-element for execution by a microcontroller of a danger detector to perform a method for detecting a dangerous situation.

Description

The present invention relates to the technical field of hazard alarm technology. The present invention relates to a fire alarm which has a primary measuring device for acquiring a physical measured variable and for outputting a measuring signal indicative of a given hazardous situation, and a microcontroller which is connected downstream of the measuring device and which is set up to evaluate the measuring signal. The present invention also relates to a method for recognizing a dangerous situation with a fire alarm. The present invention also relates to a computer-readable storage medium and a program element which contain instructions for carrying out the method according to the invention for recognizing a dangerous situation.

From the European patent application EP 0 618 555 A2 There is known a smoke detector fire alarm in which light scattered from smoke particles is received by a light receiving element and a smoke density is detected using an output level of the light receiving element. The fire detector has a temperature measuring means for measuring the ambient temperature of a light emitting element for irradiating the smoke particles and the light receiving element. Furthermore, the fire alarm has a temperature compensation means for correcting the output level of the light receiving element in accordance with the ambient temperature measured by the temperature measuring means. It also has a smoke density detection means for detecting the smoke density using the output level corrected by the temperature compensation means. The temperature compensation means and the smoke density detection means are implemented in the form of a microcomputer.

Simple optical smoke alarms based on the scattered light principle usually have a light-emitting diode which emits light in the visible or in the infrared spectral range and which preferably emits light in a scattered area in pulsed form. The scatter area is often referred to as a maze. If smoke particles are present in the scattering area, the light beams are at least partially scattered there and detected by a correspondingly mounted light receiver. The received optical power of the light receiver detected measuring light is decisive, whether e.g. rather smaller, darker particles, which arise in open fires, or rather larger, lighter particles, which arise in smoldering fires, are detected.

An important legal requirement that a smoke detector must meet is the EN54-7 standard for Europe and the essentially identical GB4715 standard for China. An essential part of this standard are the so-called test lights TF2 to TF5, which are used to test the response behavior of the hazard warning device to different types of fire. The American standard UL268 for fire detectors also knows different test fires, which, however, differ from the EN54-7 standard and are therefore not dealt with further here. In order to be allowed to bring a fire detector onto the market, all corresponding test fires with their respective different characteristics must be passed.

It is known that simple, "forward-scattering" smoke alarms are relatively insensitive to open fires with small smoke particles and can therefore only generate an alarm late after the start of a corresponding fire. This is particularly true of the TF5 test fire. Smoldering fires, which are defined by the test fire TF2, can, however, be detected relatively well with a "forward scattering" smoke alarm. In this context, a "forward scattering" smoke alarm is to be understood as a smoke alarm in which the angle between the measuring light emitted by the light-emitting diode and the measuring light detected by the light receiver is greater than 90 °, for example approx. 150 °.

In order to be able to pass all necessary test fires, it is in principle possible to adjust an optical fire detector so sensitively that all test fires are passed. However, this has the disadvantage that the probability and the frequency of false alarms, for example as a result of cigarette smoke, are increased.

In practice, an optical fire detector with only one optical signal path and with an acceptable rate of false alarms therefore usually responds very inhomogeneously to the various test fires. E.g. In the case of a pure forward spreader, the test fire TF2 will generate an alarm very early, but the test fire TF5 will trigger an alarm very late. In this context, "very early" and "very late" always mean a time specification in relation to the time limits defined in Standard 54-7.

In order to be able to pass all the required test fires, it is also known to use additional sensor inputs as alarm indicators. An additional sensor input can be coupled to a temperature sensor, for example. The corresponding combination alarm is then referred to as an "O-T" alarm. "O" stands for optical and "T" for temperature. It is also possible to use a further optical sensor with a different scattering angle and / or with a light-emitting diode emitting in a different spectral range. Such combination alarms are accordingly referred to as "O-O" hazard alarms.

An "OT" hazard alarm has the disadvantage that its construction is relatively expensive. In the production of an "OT" alarm device, there are costs for installing a temperature-sensitive component and for the temperature-sensitive component itself. also The shape of the alarm detector's housing must be adapted to the temperature-sensitive component and mechanical protective measures such as protection against accidental contact must be taken.

The production of an "O-O" hazard alarm also incurs comparatively high costs, which are caused, for example, by the additional light source and its control logic, by a required additional production adjustment and / or by shielding measures between the two separate optical paths.

The present invention is based on the device-related object of creating a hazard indicator that is as inexpensive as possible but nevertheless safe from false alarms. The present invention is based on the method-related object of improving the detection of a dangerous situation with regard to a low false alarm rate in a cost-effective manner.

This object is achieved by the subjects of the independent claims. Advantageous embodiments of the present invention are described in the dependent claims.

According to a first aspect of the invention, a hazard alarm, which can in particular be an optical smoke alarm, is described. The described hazard alarm has (a) a measuring device for acquiring a physical measured variable and for outputting a measuring signal which is indicative of a given hazardous situation, (b) a microcontroller which is connected downstream of the measuring device and which is set up to evaluate the measuring signal, and (c) a temperature measuring device for detecting a temperature and for outputting a temperature measuring signal which is indicative of the detected temperature. In the described hazard alarm, according to the invention, the temperature measuring device is integrated in the microcontroller and the microcontroller is set up in such a way that the temperature measuring signal is also taken into account when evaluating the measuring signal.

The hazard alarm described is based on the knowledge that modern microprocessors often have integrated temperature-dependent components which can be used for temperature measurement without or only with a small additional apparatus structure. The temperature measurement can be translated into a temperature value by means of an analog / digital converter, for example. This temperature value can then represent the housing temperature of the microcontroller. In this way, the heating of the housing of the microcontroller can be used as an additional hazard input for an alarm criterion of the hazard indicator in addition to the measurement signal from the measurement device.

In the described hazard alarm, the temperature measuring device is integrated in the microcontroller. This means that a common component housing is provided for the microcontroller and the temperature measuring device. Typically, “integrated” also means that it is not possible to separate the temperature measuring device from the microcontroller without destroying at least one of the two components “microcontroller and temperature measuring device”.

It should be noted that the sensitivity and the response time of the temperature measuring device integrated in the microcontroller will generally not be as good as, for example, a separate temperature-sensitive resistor which is used in a known manner for special temperature indicators. Such temperature-sensitive resistors such as NTC resistors (negative temperature coefficient resistors) are usually spatially arranged in a temperature detector in such a way that the ambient air flows optimally against them and respond quickly due to a preferably low thermal mass. Rapid temperature changes can thus be detected quickly. The temperature measuring device integrated in the microcontroller can therefore usually not completely replace the NTC resistance of a thermal alarm indicator, so that, for example, the thermal standard EN54-5 relevant for hazard alarms could not be met. An increase in the housing temperature of the microcontroller detected by the integrated temperature measuring device can, however, contribute to both increasing the sensitivity of the hazard alarm and reducing the probability of triggering a false alarm in a simple manner and in particular without additional expenditure on equipment.

In the described hazard alarm, the temperature measurement signal of the temperature measurement device integrated in the microcontroller is used in addition to the measurement signal of the actual measurement device as a further or additional hazard alarm input. In order to implement this additional alarm input, therefore, as a rule, no additional expenditure on equipment is required in an advantageous manner. This applies in any case to those microcontrollers which anyway have a suitable temperature measuring device.

The measuring device can be, for example, a gas measuring device which has a chemical sensor to which gas molecules from the ambient air are chemically bound on the sensor surface. The bound gas molecules can give off electrical charges that change the electrical conductivity of the sensor's semiconductor material. The gases to be detected can be fire gases such as CO2. From a certain concentration in a monitored room, the described hazard alarm generates a hazard message or an alarm message.

It should be noted that the hazard alarm can of course also have several measuring devices may have, wherein at least one of the measuring devices is combined with the described temperature measuring device with regard to a common signal processing. However, the measurement signals provided by all measurement devices are preferably combined with one another.

According to a further exemplary embodiment of the invention, the temperature measuring device is a temperature measuring diode. The use of a temperature measuring diode as a temperature measuring device integrated in the microcontroller has the advantage that it can be produced with a semiconductor production of the microcontroller without additional process steps.

Temperature measuring diodes are already present in many modern microcontrollers. Therefore, the described hazard alarm can be constructed with simple electronic standard components and can thus be implemented in an inexpensive manner.

According to a further exemplary embodiment of the invention, the measuring device is an optical measuring device which has (a) a light transmitter set up to emit a measuring light and (b) a light receiver set up to receive at least part of the measuring light. This means that the described hazard alarm works analogously to known so-called O-T (optical temperature) alarm alarms, but a temperature-sensitive resistor that is usually used is replaced by the temperature measuring device integrated in the microcontroller. As a rule, this reduces the accuracy of the temperature measurement and slows down the response behavior in the event of temperature changes. The temperature measurement signal can, however, be used for evaluating the measurement signal of the primary measurement device and thus contribute to a higher sensitivity and, at the same time, to a lower probability of false alarms compared to hazard alarms with only a single measurement device. In any case, the described hazard alarm can be manufactured significantly more cheaply compared to known O-T hazard alarms.

As already described above, the temperature measuring device essentially detects the rise in the housing temperature of the microcontroller. Even if the temperature measuring device is inevitably coupled with a comparatively large thermal mass, in the event of a fire, taking into account the rise in the housing temperature can contribute to complying with the EN54-7 regulation, which is relevant for optical fire detectors, even with a less sensitive optical adjustment and therefore protecting against false alarms increase significantly.

It should be noted that the optical measuring device can be used to measure light scattering caused by smoke particles and / or shadowing caused by smoke particles. In the case of the measurement of light scattering, the light receiver is preferably arranged at an angle of, for example, greater than 10 ° relative to the optical axis of the measurement light emitted by the light transmitter. This means that only scattered measuring light reaches the light receiver, which generates a corresponding measuring signal in the presence of smoke particles. In the case of measuring light absorption, the light receiver is preferably arranged relative to the light transmitter in such a way that at least some of the unscattered measurement light reaches the light receiver even when there is no smoke. The light intensity measured by the light receiver is reduced in this case by the presence of light absorbing or light scattering smoke particles.

The described primarily optical hazard alarm can be calibrated less sensitively thanks to the additional thermal hazard input compared to a known purely optical hazard alarm. This has the advantage that the comparison process for generating or initiating a hazard message is considerably easier. This is due to the fact that the specified tolerances are considerably narrower for more sensitive alarm devices and such sensitive alarm devices are therefore much more difficult to manufacture within the narrow prescribed tolerances of the EN54-7 standard. According to a further exemplary embodiment of the invention, the hazard alarm additionally has an alarm housing, in the spatial center of which the microcontroller is arranged. This has the advantage that the thermal directional dependency of the hazard alarm described is low. This in turn means that a temperature change caused by a heat source can be detected with constant sensitivity regardless of the direction in which the heat source is located, starting from the hazard alarm described.

It should be noted that it is not absolutely necessary that the housing have a perfectly symmetrical shape. In the case of an asymmetrical shape, the microcontroller is then preferably arranged at the point within the housing at which heat sources, such as a fire, can be detected as independent of direction as possible.

According to a further exemplary embodiment of the invention, the hazard alarm additionally has at least one heat-conducting element which is connected to a housing of the microcontroller.

By thermally coupling materials that conduct heat well, which can preferably come into thermal contact with the outside air of the alarm, the temperature measuring device of the microcontroller can better detect temperature changes in the air surrounding the alarm. The materials that conduct heat well and / or the at least one heat-conducting element can be arranged in such a way that the outside air of the hazard alarm flows around or against them. The heat conduction element can also be referred to as a so-called thermal discharge pad.

The described use of at least one heat conducting element has the advantage that a better thermal coupling of the microcontroller to its surroundings and thus a shorter response time of the microcontroller housing to temperature changes can be guaranteed.

The heating element can be used, for example, to thermally couple a shielding plate of the photodiode serving as the light transmitter to the housing of the microcontroller. Since the shielding bleach of the photodiode is typically located within the labyrinth through which air flows or within the optical measuring chamber of the alarm indicator, the thermal coupling of the temperature measuring device to the ambient air is improved in a simple and efficient manner and thus the thermal time constant of the housing is effectively reduced.

According to a further aspect of the present invention, a method for recognizing a dangerous situation, in particular for recognizing smoke, is specified. The specified method comprises (a) recording a physical measured variable and outputting a measurement signal which is indicative of a given dangerous situation by means of a measuring device, (b) recording a temperature and outputting a temperature measurement signal which is indicative of the recorded temperature, by means of a temperature measuring device integrated in the microcontroller, and (c) an evaluation of the measurement signal, taking into account the temperature measurement signal, by means of the microcontroller which is connected downstream of the measuring device.

The stated method is based on the knowledge that simple hazard alarms with only one sensor input can be upgraded in a simple manner and in particular without additional equipment expenditure by using a temperature measuring device, which is already present in many modern microcontroller components, for temperature measurement. A measured temperature value achieved in this way is then taken into account when evaluating the primary measurement signal of the measurement device. Thus, a danger message initiated by the microcontroller no longer depends exclusively on the output primary measurement signal of the measuring device but also on the temperature measurement signal of the temperature measuring device integrated in the microcontroller.

The described method has the advantage that it can be carried out by many conventional alarm indicators without any equipment modifications. This also applies to alarm indicators which initially only have a single alarm input or at least initially no thermal alarm input. The only requirement for the implementation of the specified method is the presence of a microcontroller which has an integrated temperature measuring device. In this case the described method can be implemented by simple programming, i. can be implemented using software.

According to an exemplary embodiment of the invention, the method additionally includes amplifying the changes over time in the measurement signal and / or the temperature measurement signal. This means that, for example, in the event of a temperature rise, the rise over time of the temperature measurement curve recorded by the temperature measurement device is amplified. In other words, this means that the slope of the temperature measurement curve is increased. This can be done in a known manner, for example, by a suitable software algorithm and / or by an appropriately designed electronic circuit and thus in hardware.

The described amplification of the temporal changes has the advantage that the temporal response behavior of the integrated temperature measuring device, which is very much slowed compared to an external NTC, can, after amplification, at least approximate to the response of an external temperature sensor, for example an NTC.

According to a further exemplary embodiment of the invention, only a relative change in the temperature measurement signal is taken into account when the microcontroller evaluates the measurement signal.

Taking into account only relative temperature changes has the advantage that calibration of the temperature measuring device can be dispensed with. This applies both during the manufacture of the alarm indicator and during, for example, longer operation of the alarm indicator.

By dispensing with a calibration of the temperature measuring device, the entire alarm indicator can be produced just as quickly as a less powerful conventional alarm indicator, which only has one sensor input and, if necessary, does not use a temperature measuring device integrated in a microcontroller at all for evaluating and initiating a hazard message .

According to a further exemplary embodiment of the invention, the temperature measurement signal is indicative of an absolute temperature.

Taking into account a temperature measurement signal which is indicative of an absolute temperature value has the advantage that not only temperature changes but also absolute temperature values can be taken into account when evaluating the primary measurement signal. As a result, the hazard alarm can be adapted even more specifically to certain ambient conditions and, on the one hand, high sensitivity and, on the other hand, a low false alarm probability of the hazard alarm can be achieved.

Of course, an absolute temperature value must be taken into account before and possibly calibration or calibration of the temperature measuring device also during operation of the hazard alarm. To do this, the temperature measuring device must be compared with a reference temperature.

According to a further exemplary embodiment of the invention, the measuring device is an optical measuring device and the temperature measuring signal is used to compensate for temperature-dependent effects of the optical measuring device.

Thermal effects within the entire temperature-dependent optical path can preferably be compensated for by means of the absolute temperature measurement signal. In this context, the term optical path is not only to be understood as the entire optical path between the light transmitter and the light receiver, the optical path also includes optical or optoelectronic components such as the light transmitter and the light receiver. When the temperature changes, not only the light output of the light transmitter but also the sensitivity of the light receiver can change. Likewise, if necessary, a set relative adjustment between the light transmitter and light receiver can change, for example, as a result of thermal stresses in the holding elements of the hazard alarm. All these thermal effects can, as far as they are reproducible and known in advance, be taken into account in the evaluation of the primary measurement signal and compensated in a suitable manner.

As already explained above, the temperature measurement signal essentially reflects the housing temperature of the microcontroller. Thus, in the method described, the housing temperature is used for temperature compensation of the optical path. This improves the response behavior of the alarm indicator, especially at very cold and very hot temperatures.

In this context, reference is made to another component of the EN54-7 standard. Accordingly, the response behavior of the alarm indicator at 55 degrees may deviate from the response behavior at 25 degrees by a maximum of a certain factor. The described compensation of temperature-dependent effects thus contributes to the fact that the corresponding optical measuring device can more easily meet the EN54-7 standard.

According to a further aspect of the invention, a computer-readable storage medium is described in which a program for recognizing a dangerous situation is stored. If the program is executed by a microcontroller of a hazard alarm of the type described above, it is set up to carry out the above-specified method for recognizing a hazardous situation.

According to a further aspect of the invention, a program element for recognizing a dangerous situation is described. The program element, when it is executed by a microcontroller of a hazard indicator of the type described above, is set up to carry out the above-specified method for recognizing a hazardous situation.

The program and / or the program element can be implemented as computer-readable instruction code in any suitable programming language such as, for example, JAVA, C ++, etc. The program and / or the program element can be stored on a computer-readable storage medium (CD-ROM, DVD, removable drive, volatile or non-volatile memory, built-in memory / processor, etc.). The instruction code can program a computer or other programmable device to perform the desired functions. Furthermore, the program and / or the program element can be provided in a network such as the Internet, from which it can be downloaded by a user if necessary.

The invention can be implemented both by means of a computer program, e.g. software, as well as by means of one or more special electrical circuits, i. in hardware or in any hybrid form, i.e. using software components and hardware components.

Figur 1

zeigt in einer schematischen Darstellung den Aufbau eines Gefahrmelders gemäß einem Ausführungsbeispiel der Erfindung

Figur 2

zeigt ein experimentell gemessenes Ansprechverhalten des in Figur 1 dargestellten Gefahrmelders für ein Testfeuer TF5 gemäß der Norm EN54-7.

Further advantages and features of the present invention emerge from the following exemplary description of a currently preferred embodiment.

Figure 1

shows in a schematic representation the structure of an alarm indicator according to an embodiment of the invention

Figure 2

shows an experimentally measured response behavior of the in Figure 1 shown danger indicator for a test fire TF5 according to the standard EN54-7.

At this point it should be noted that the same reference symbols are used in the drawing for the same components.

Figure 1 FIG. 11 shows a schematic representation of a forward scattering optical hazard alarm 100. The upper part of FIG Figure 1 shows the hazard alarm 100 in a side view parallel to an assembly plane. The mounting level can, for example, be the ceiling of a room to be monitored. The lower part of Figure 1 shows the hazard alarm 100 in a plan view, the viewing direction being oriented perpendicular to the mounting plane.

The hazard alarm 100 has a primary optical measuring device which has a light transmitter 110 in the form of a light-emitting diode and a light receiver 115 in the form of a photodiode. According to the embodiment shown here, the optical measuring device works according to the known scattered light principle. In this case, in a known manner, the light receiver 115 only detects a measurement light when this measurement light is scattered on aerosols or smoke particles. The in Figure 1 Hazard indicator shown is thus a smoke alarm 100, which is also suitable for detecting fires. According to the exemplary embodiment shown here, the light-emitting diode 110 is set up to emit measuring light in the infrared spectral range.

The smoke detector 100 has a detector housing 140. A substrate 130 in the form of a printed circuit board is located within the housing 140. Below the printed circuit board 130, the detector housing 140 forms an optical chamber 142 into which the smoke particles to be detected can enter via an air stream 150. In order to allow air to enter as undisturbed as possible, air slots (not shown) are formed in the detector housing 140.

The smoke alarm 100 also has a microcontroller 120 which is coupled in a known manner both to the light transmitter 110 and to the light receiver 115. The microcontroller 120 is on the one hand for controlling the light-emitting diode 110, possibly via in Figure 1 set up driver circuits not shown. On the other hand, the microcontroller 120 is set up to evaluate an optical measurement signal generated by the photodiode 115.

According to the exemplary embodiment shown here, the microcontroller 120 has a temperature measuring device 125 designed as a temperature measuring diode. The temperature measuring diode 125 is integrated in the microcontroller 120. This means that the microcontroller 120 and the temperature measuring diode 125 are arranged in a common housing.

The microcontroller 120 is set up, for example by means of suitable programming, in such a way that a temperature measurement signal from the temperature measurement diode 125 is also taken into account when evaluating a measurement signal generated by the photodiode 115. This means that the evaluation by the microcontroller 120 corresponds to the evaluation for a known so-called O-T hazard alarm. The described hazard alarm 100 differs from a known so-called O-T hazard alarm, among other things, in that instead of a separate temperature measuring resistor such as an NTC resistor, a temperature measuring device 125 integrated in the microcontroller 120 is used for temperature measurement.

According to the exemplary embodiment shown here, the circuit board 130 serves not only for electrical wiring or the electrical contacting of electronic and optoelectronic components of the smoke detector 100. According to the exemplary embodiment shown here, the circuit board 130 also serves as a mechanical holder for these components.

In order to ensure a good thermal coupling of the temperature measuring diode 125 to the incoming ambient air 150, heat conducting elements 134 are provided. The heat conducting elements 134, which are also referred to as thermal pads, represent a heat-conducting connection between the temperature measuring diode 125 and a heat exchange element 116. The heat-conducting connection is made via a soldered connection through a through hole 132 to the heat exchange element 116 In the exemplary embodiment, the heat exchange element is a metallic shield 116 of the photodiode 115 Figure 1 As can be seen, ambient air 150 flows against or around metallic shield 116, so that heating of ambient air 150, in particular due to an external source of fire, is quickly detected by integrated temperature measuring device 125.

Figure 2 shows a diagram 260 in which the response behavior of the in Figure 1 illustrated optical hazard alarm 100 for a test fire TF5 according to the standard EN54-7. The optical measurement signal detected by the optical measurement device is shown as a function of time with reference number 270. The time zero marks the beginning of the test fire TF5. The optical measurement signal 270 is shown in relative units (see the ordinate on the left-hand side of the diagram 260).

The temperature measurement signal detected by the temperature measurement device 125 is shown as a function of time with the reference numeral 280. The time axes of the optical measurement signal 270 and of the temperature measurement signal 280 are identical. The temperature measurement signal 280 is shown in degrees Celsius (see the ordinate on the right-hand side of the diagram 260).

How out Figure 2 As can be seen, the measured temperature rise 280 lags behind the rise of the optical measurement signal 270 in time. Nevertheless, the information provided by the temperature measurement signal 280 can also be taken into account for the evaluation of the optical measurement signal 270. The measured temperature rise ΔT is in fact already approx. 4 degrees Celsius 200 seconds after the start of the test fire TF5. By means of a combined evaluation of the optical measurement signal 270 and the temperature measurement signal 280, for example, the probability of triggering a false alarm can be reduced considerably while the reliability for the detection of an actual fire is nevertheless high. This is true at least in comparison to a simple optical smoke alarm with only one optical alarm input.

The vertical line marked with the reference numeral 290 in the diagram 290 represents the upper limit of the measured test fire TF5 according to the standard EN54-7. In the measured, depicted test fire, this limit is 200 seconds. If an alarm message only occurs at a later point in time, then in the case shown, the corresponding fire detector does not meet the EN54-7 standard.

It should be noted that the rise in the temperature measurement signal 280 can also initially be amplified and only then can be used for a common signal evaluation. This means that the Slope of the temperature measurement signal 280 is artificially increased. This can be done in a known manner, for example, by a suitable software algorithm and / or by an appropriately designed electronic circuit and thus in hardware.

Of course, the rise in the optical measurement signal 270 can also be amplified. In addition to the measured increase, the increased increase can also be used as an additional alarm criterion. In this way, the alarm time of the corresponding alarm can be further reduced. Furthermore, the optical channel, which is prone to false alarms, can be designed to be even less sensitive.

Claims (7)

1. Fire alarm with

   • a measuring facility (110, 115) for detecting a physical measurement variable and for outputting a measurement signal (270) which are indicative of a predetermined hazard situation,

   • a temperature measuring facility (125) for detecting a temperature and for outputting a temperature measurement signal (280) which is indicative of the detected temperature, and

   • a microcontroller (120), which is connected downstream of the measuring facility (110, 115) and which is set up to evaluate the measurement signal (270) in such a manner that the temperature measurement signal (280) is also taken into account when the measurement signal (270) is evaluated, and

   characterised in that
   the temperature measuring facility (125) is integrated in the microcontroller (120), wherein the temperature measurement signal is used as an additional hazard input for an alarm criterion of the fire alarm.
2. Fire alarm according to claim 1, wherein the temperature measuring facility is a temperature measuring diode (125).
3. Fire alarm according to one of claims 1 to 2, additionally featuring

   • an alarm housing (140),

   wherein the microcontroller (120) is disposed spatially in the centre of the alarm housing (140).
4. Fire alarm according to one of claims 1 to 3, additionally featuring

   • at least one heat conducting element (134) which is connected to a housing of the microcontroller (120).
5. Fire alarm according to one of claims 1 to 4, wherein the fire alarm is an optical fire alarm and wherein the measuring facility is an optical measuring facility, featuring

   - a light transmitter (110), set up to transmit a measurement light, and

   - a light receiver (115), set up to receive at least some of the measurement light.
6. Fire alarm according to one of claims 1 to 4, wherein the measuring facility is a gas measuring facility for identifying combustion gases.
7. Fire alarm according to claim 6, wherein the gas measuring facility features a chemical sensor with a semiconductor material for identifying the combustion gases, wherein gas molecules from the ambient air are bonded to a sensor surface of the chemical sensor, and wherein the bonded gas molecules are able to release electrical charges which alter the electrical conductivity value of the semiconductor material of the chemical sensor.

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